Hi
As a scientist (going to study dentistry) I am definitely biased! I loved Biology at A Level, but yes, it did get a tad boring at A2. That was only because I had absolutely no interest in muscles or how they worked, so I found this v tedious, whereas my friend who wanted to study physiotherapy at the time absolutely LOVED it. But I would definitely recommend it - it is a valuable A Level to have. I also took Chemistry, and at the time I absolutely haaaaated it, but looking back it was quite interesting at some points. So I would say Biology and Chemistry
they open a lot of doors for you as they are regarded as extremely difficult A Levels.
I would have loved to study Psychology, I think it's sooo interesting! So I think that would be a good choice - some stuff covered in Biology and Chemistry also overlaps (had a friend who studied those three) and she was always saying how they'd covered it in Psychology, but that Biology really helped her understand it more.
As for a fourth.. pick something you enjoy
if your passion is photography - go for it! For me it was Music.. although I wouldn't say it was easy it was definitely a lot more relaxing than working out equations!
So thats Biology, Chemistry, Psychology and Photography
they will open up a lot of doors for you and you have quite a wide scope as to what you can apply for! I'd recommend you get work experience now - it will help you decide what you want to do in the future
also, don't feel pressured into applying to university! You can always take a gap year and reapply later once you're sure. There is also the possibility of apprenticeships
I hope this helps! Good luck